233-8 Tempo and Mode: Applying Phylogenetic Natural History to Integrate Micro- and Macroevolution across the K-Pg Boundary

Session: Impact Cratering and the Evolution of Life

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Unraveling the interactions among major events in Earth’s history and macroevolutionary patterns is a fundamental challenge in evolutionary biology. “Phylogenetic Natural History” addresses this challenge by combining explicit hypothesis testing with data-rich phylogenetic inference to uncover the mechanisms behind evolutionary transitions. My research program applies this approach and aims to integrate the traditionally isolated fields of natural history, paleontology, genomics, and data science to study evolutionary patterns across different spatial and temporal scales. Here, I highlight recent work that treats the tempo and mode of genome evolution as complementary axes of life-history variation. Using models capable of detecting time-heterogeneous evolutionary processes, I investigate the end-Cretaceous (K–Pg) mass extinction—a macroevolutionary contingency that rewired the evolutionary trajectories of surviving lineages—and analyze its genomic signature across underexplored dimensions of biodiversity. In this context, birds are a powerful example: coordinated shifts in developmental strategies, body size, and metabolic physiology across the K–Pg boundary may align with temporary increases in nucleotide substitution rates and changes in nucleotide composition. Together, these genomic and phenotypic shifts provide compelling indirect evidence for the “Lilliput effect,” a phenomenon in which lineages surviving mass extinctions tend to exhibit reduced body size. By linking changes in genomic architecture to the origination of higher taxa, this work illustrates how studying deep-time contingencies like the Chicxulub impact can yield critical insights into the forces driving evolutionary innovation and resilience, and how such events shape the trajectory of life over tens of millions of years.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-11105

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